Yarn cutting means for knitting machine



Aug. 28, 1962 G. BILL; 3,050,970

YARN CUTTING MEANS FOR KNITTING MACHINE Filed Feb. 10, 1959 3 Sheets-Sheet 1 10c I! 9 8 1 o I Fig.1 j W x I I Aug. 28, 1962 G. BILL! 3,050,970

YARN CUTTING MEANS FOR KNITTING MACHINE Filed Feb. 10, 1959 F1 4 3 Fig. 5

3 Sheets-Sheet 2 1962 G. BILL] 3,050,970

YARN CUTTING MEANS FOR KNITTING MACHINE Filed Feb. 10, 1959 3 Sheets-Sheet 5 United States Patent 3,050,970 Y CUTTING MEANS FOR KNITTING MACIWE Giorgio Eilli, Viale Torricelli 23, Florence, Italy Filed Feb. 10, E59, Ser. No. 792,396 Claims priority, application Italy Feb. 14, 1958 8 @laims. (Cl. 66-146) This invention relates to improvements in circular knitting machines, especially for the manufacture of stockings, socks and the like. These machines produce fabrics characteristically provided with extensions or tails of yarns extending out of the fabric. These extensions are produced at both the start and end of knitting of the fabric. Generally the operator of the machine knitting the fabric must cut these yarn extensions. This operation is time consuming, costly and often results in damage to the fabrics due to difficulty in cutting the yarns particu larly when the cutting must be done at high speed.

In known circular knitting machines there has been provided a cutting and retaining means including a nipper and spring on the cover overlying the Working zone of the needles on the needle cylinder. The arrangement is designed for temporarily gripping the yarn at the start and end of working each yarn. The yarn must be withdrawn from the spring during return movements of the needles which have knitted the yarn, in order to bring it back into working position. A knife cutting system is provided in the machine.

This arrangement is slow, and is unsatisfactory since the yarn catches in the spring and breaks are frequent, necessitating stopping the machine for servicing.

The present invention has as an object an improved cutting arrangement for yarn in a circular knitting machine, including a suction duct which yieldably retains ends of yarns extending from yarn guides until they can be withdrawn by the working needles.

A further object is to provide a cutting arrangement which produces such short tails or extensions of yarn at the beginning and end of Working of the yarn in the fabric that no subsequent cutting or trimming of the yarn ends are necessary.

Another object is to provide a cutting arrangement in a circular knitting machine including one or more suction ducts, and yarn cutting means which may be incandescent electrical resistors, electric arc discharge devices, etc.

According to the invention, there is provided an arrangement which efiects cutting of the yarn when a yarnguide is raised for excluding a yarn from working. The cutting system. effects cutting near the last needle which has picked up and has stitched the yarn to be cut. The arrangement is such that a residual length of yarn is guided by the yarn-guide into the suction duct, and has a length determined b ythe relative positions of the yarn-guide and the stitching position of the needles. This last arrangement allows the yarn which has been stitched to be cut to the desired residual length. Subsequently, the cut end of the yarn, which enters the duct is seized by a needle at the beginning of a new working cycle and the following needles engage the yarn slidably and extract the yarn from the duct against the suction therein. This sliding action occurs because of the greater pull on the yarn by the needles opposed to the lesser pull due to suction in the duct. Thus, when the yarn is stitched by one needle after it is lowered, the residual yarn portion, which protrudes from the fabric, will have the desired length. In the stitching position the yarn cannot slide and the return of the yarn is begun by the yarn-guide.

According to the invention, the duct has a substantially flattened form and an intake mouth or inlet, which extends from the yarn feed zone, that is, from the location of the yarnguide through a predetermined arc to a posi tion over the stitching location of the needle cylinder. At the end of the duct (in the direction of rotation of the needle cylinder) there is located the yarn cutting system. Means are provided to assure such a positioning of the yarn that the portion of the residual yarn emerging out of the yarn-guide is drawn back by suction in the duct in the most appropriate position to be inserted again later between the needles to be picked up and then stitched.

A cutting system may be advantageously formed by a small electrical resistor designed to cut the yarn when this yarn is brought near to it. Other cutting systems may be provided near to the path of movement of the needles such as a voltaic are or the like.

In an arrangement of a machine provided with plural yarn feed positions, there may be provided as many intake or suction arrangements. Two or more ducts may also be so combined as to determine either a continuous or divided suction intake for the cut yarns.

The invention will be better understood from the following description and the accompanying drawing, wherein:

FIG. 1 is an elevational view partly in vertical axial section of a needle cylinder according to the invention.

FIG. 2 is a section taken along the line II-II of FIG. 1.

FIG. 3 is a side view taken along the line III-III of FIG. 2.

FIGS. 4, 5, 6 and 7 illustrate some steps at the start of Working with a certain yarn.

FIG. 8 is a diagrammatical cylindrical development of a needle cylinder.

FIG. 9 illustrates an embodiment including a yarn cutting arrangement.

FIGS. 10 and 11 illustrate two embodiments adapted for a two-feed knitting machine.

In the accompanying drawing, 1 denotes a needle cylinder provided with vertical grooves to house needles 2. A cover 3 is located over the needle cylinder. A yarn locking arrangement for the yarns coming from the yarnguides 4a, 4b, etc., is located on the cover 3. The stitching zone 5 shown in FIG. 2 in plan view corresponds to the location of the lowered needles 2 in the cylinder 1 where the needles stitch the yarn.

There is provided according to FIGS. 1 to 8 a duct 8 on cover 3. The duct has an elongated flattened suction mouth or inlet adjacent the needle working zone between the feed zone of the yarn-guides 4a, 4b, etc. and the stitching zone 5. The duct 8 is provided. with a tapered union 9 serving as a suction conduit. The suction efiects the locking of the yarns such as those denoted by 10, coming from the yarn-guides 4a, 4b, etc. The suction may be obtained from a suitable suction producing apparatus (not shown). In the drawing, ltla denotes the portion of yarn which is instantaneously located between a yarn-guide and a needle which has risen; 10b denotes the residual portion of a yarn engaged by the needles. This portion of yarn is submitted to the suction in the duct 8; denotes the portion of yarn which is in the raised yarn-guide such as 44: of FIG. 1, which yarn portion is drawn in by the duct 8.

At the end of the duct in the direction of the motion of the needle cylinder 1, there is arranged a cutting means located near to the circular path of movement of the needles. According to the embodiment of FIGS. 1 to 8, the cutting means is formed by a wire 11. made incandescent by the passage of a current, which instantaneously cuts the yarn moving near to it, either by melting or by combustion. Near the cutting zone there is also provided, on the duct, a guide element formed by a roof extension 12 which assures the best position of the cut residual yarn to be sucked in by the duct 8.

When the yarn-guide is raised as denoted by 4a, the

portion of the yarn 10c which is extended from the raised yarn-guide 4a into the duct 8, is sucked in by the latter with a tension which is lower than the stress required to slide the yarn coming from the yarn-guide. When a yarn-guide such as that denoted by 4b in FIG. 1 is lowered, a needle 2a first seizes the yarn and owing to the rotation of cylinder, tends to bring it into its path of the cylinder. The subsequent needles 2 similarly engage the yarn. However, owing to the lesser tension with which the yarn 10c and the residual portion of the yarn ltib is drawn towards the duct 8, along the are between the feed zone and the stitching zone 5, the needles which have engaged the portion of the yarn 10c and which start working the yarn, cause the yarn to slide towards the needles. This shortens the residual portion 1012 without the yarn unwinding from the yarnguide. The sliding continues until the needle 2a, which first has engaged the yarn of the yarn-guide which has been lowered, reaches the stitching Zone 5 at this point the yarn bound to the fabric cannot slide any longer and there remains extending out of the fabric the residual yarn ltib indicated in FIG. 6. The tail b is puiled out of the duct while the needles rotate as indicated in FIG. 4. An intermediate position of the tail is indicated by one thereof in FIG. 5. A final position is indicated in FIG. 6. There the sliding of the residual portion of yarn liib ceases and the return of the yarn begins at 10a. The residual portion of the yarn ltlb is reduced to that required and permissible in finished fabric. The tail 10b in the fabric is formed during rotation of the cylinder as shown in FIG. 7.

When a yarn-guide is raised (as for instance the yarnguide 4a in FIG. 2), while another yarn-guide (such as that denoted by 40) is lowered and has begun to feed or supply the yarn to the fabric, the yarn portion 10a between the yarn-guide 4a and the raised needle 2b, which has picked up the yarn from the yarn-guide 4a, is lengthened. While yarn portion 10a passes under the duct extension 12 it progressively approaches the resistor 11 until the latter cuts the yarn at such a distance from the needle 2b that the residual portion 10d of the yarn, emerging out of the bond formed by the last needle 2b is that required and permissible When the fabric is finished. The portion 10a of the yarn remaining included between the yarn-guide 4a and the resistor 11 is presented at the opening of the duct 8 where it is retained in duct extension 12. The yarn end is drawn by the suction set up by duct 8 into the duct until it assumes the position indicated at 100 with respect to the raised yarn-guides. Upon lowering of the yarn-guide again, the yarn end 10c is again drawn out of the duct as already described. The position of the resistor 11 determines the length of the portion of the yarn 10b which remains at the start of the working with a certain yarn, and determines the length of the residual yarn 10d at the end of the working.

According to the modification illustrated in FIG. 9, instead of the cutting resistor, there is provided the shears formed by the stationary member 15 and the movable member 16. The shears are raised through a rocker arm 18 and a tie rod 17 by the lever 19. The lever is controlled by a tappet 20 controlled, in turn, by a cam 21. The movement of the blade 16 is effected by tripping tappet 20 as it rides on cam 21 and by the action of springs 22, 23. The cutting occurs near the path of movement of the needles 2 to leave a limited final length 10d of yarn.

According to 'FIG. 10, there is provided a duct 24 much more arcuately extended than that of duct 8 previously described. Duct 24 is employed in a two-feed machine having two sets of yarn-guides 25 and 26. The duct 24 is provided with a baffle or interruption 27 in its month. There is provided at the baffle 27 one resistor 28 or equivalent cutting means. A second resistor 29 is provided at the end of the duct. Duct extensions 30 and 31 d equivalent to extension 12 of the prior embodiment are also provided.

According to FIG. 11, there may be provided two independent ducts 33, 54 forming spaced parts of a single remote suction conduit. There may also be provided more than two ducts in the case of machines having more than two yarn feeds.

In addition to cutting systems as described, there may be provided means for cutting supplementary yarns (such as those for sole and a reinforced heel of a stocking) to form tails one or two millimeters in length. This may include a resistor or mechanical cutting system with a pneumatic locking device. A yarn cutting resistor may also be located above the needles 2 to cut the yarn leaving tails 10c and 10d of proper length. A suction pick-up for the yarn will be provided in any case.

The drawing only illustrates certain embodiments as examples of the invention. The invention may be varied in the forms and arrangements without however departing from the scope of the concept defined by the appended claims.

What I claim is:

1. In a circular knitting machine having a rotary needle cylinder; yarn guides lowerable to feed a yarn and raisable to interrupt the feed of the yarn; movable needles slidable in grooves in said cylinder at a stitching location thereof for engaging the yarn to stitch the same into fabric and a stationary cover overlying the cylinder; a yarn engaging device comprising a suction duct having an arcuate open inlet disposed on said cover adjacent a rotary path of movement of the needles at said stitching location of the cylinder; and a yarn severing device located at an end of said inlet in the direction of rotation of the cylinder for cutting a portion of yarn engaged in said inlet under suction.

2. In a circular knitting machine having a rotary needle cylinder; yarn guides lowerable to feed a yarn and raisable to interrupt the feed of the yarn; movable needles slidable in grooves in said cylinder at a stitching location thereof for engaging the yarn to stitch the same into fabric and a stationary cover overlying the cylinder; a yarn engaging device comprising a suction duct having an arcuate open inlet disposed on said cover adjacent a rotary path of movement of the needles at said stitching location of the cylinder; and a yarn severing device located at an end of said inlet in the direction of rotation of the cylinder for cutting a portion of yarn engaged in said inlet under suction, said duct having a roof portion extended at said inlet for engaging and guiding cut ends of yarn into the inlet.

3. In a circular knitting machine having a rotary needle cylinder; yarn guides at a plurality of spaced yarn feed positions; movable needles slidable in grooves in said cylinder for engaging the yarns to stitch the same into fabric at spaced stitching locations of the cylinders; a stationary cover overlying the cylinder; a yarn engaging device comprising a plurality of suction ducts each having an arcuate open inlet disposed on said cover adjacent a rotary path of movement of the needles for receiving yarn portions, the inlets being located at respective stitching locations associated with the several feed positions, and a yarn severing device located at the end of each inlet in the direction of rotation of the cylinder.

4. In a circular knitting machine having a rotary needle cylinder; yarn guide-s lowerable to feed a yarn and raisable to interrupt the feed of the yarn; movable needles slidable in grooves in said cylinder for engaging the yarn to stitch the same into fabric, and a stationary cover overlying the cylinder; a yarn engaging device comprising a suction duct having an arcuate open inlet disposed on said cover adjacent a rotary path of movement of the needles; and a yarn severing device located at an end of said inlet in the direction of rotation of the cylinder for cutting a portion of yarn engaged in said inlet under suction, said inlet being sufficiently long to exceed in angular extent two yarn feed positions for the needles; a battle dividing said inlet into separate openings; and another yarn severing device located at said battle for cutting yarn entering the inlet between said baflle and the other end of said inlet.

5. In a circular knitting machine having a rotary needle cylinder; yarn guides lowerable to feed a yarn and raisable to interrupt the feed of the yarn; movable needles slidable in grooves in said cylinder for engaging the yarn to stitch the same into fabric, and a stationary cover overlying the cylinder; a yarn engaging device comprising a suction duct having an arcuate open inlet disposed on said cover adjacent a rotary path of movement of the needles; and a yarn severing device located at an end of said inlet in the direction of rotation of the cylinder for cutting a portion of yarn engaged in said inlet under suction, said inlet being sufliciently long to exceed in angular extent two yarn feed positions for the needles; a battle dividing said inlet into separate openings; and another yarn severing device located at said baflle for cutting yarn entering the inlet between said baffle and the other end of said inlet, said duct having a roof portion extended at said baffle and at said one end of the inlet for engaging and guiding cut ends of yarns into the inlet.

6. In a circular knitting machine having a rotary needle cylinder; yarn guides lowerable to feed a yarn and raisable to interrupt the feed of the yarn; movable needles slidable in grooves in said cylinder for engaging the yarn to stitch the same into fabric, and a stationary cover overlying the cylinder; a yarn engaging device comprising a suction duct having an arcuate open inlet disposed on said cover adjacent a rotary path of movement of the needles; and a yarn severing device located at an end of said inlet in the direction of rotation of the cylinder for cutting a portion of yarn engaged in said inlet under suction, said yarn severing means being an electrical resistance wire effective to sever the yarn when heated.

7. In a circular knitting machine having a rotary needle cylinder; yarn guides lowerable to feed a yarn and raisable to interrupt the feed of the yarn; movable needles slidable in grooves in said cylinder for engaging the yarn to stitch the same into fabric, and a stationary cover overlying the cylinder; a yarn engaging device comprising a suction duct having an arcuate open inlet disposed on said cover adjacent a rotary path of movement of the needles; and a yarn severing device located at an end of said inlet in the direction of rotation of the cylinder for cutting a portion of yarn engaged in said inlet under suction, said yarn severing means being shears having stationary and movable members; and cam means operatively connected to actuate the shears and operated in coordination with rotation of the cylinder for cutting the yarn at ends of knitting cycles thereof.

8. In a circular knitting machine having a rotary needle cylinder; y-arn guides lowerab le to feed a yarn and raisable to interrupt the feed of the yarn; movable needles slidable in grooves in said cylinder for engaging the yarn to stitch the same into fabric, and a stationary cover overlying the cylinder; a yarn engaging device comprising a suction duct having an arcuate open inlet disposed on said cover adjacent a rotary path of movement of the needles; and a yarn severing device located at an end of said inlet in the direction of rotation of the cylinder for cutting a portion of yarn engaged in said inlet undler suction, said inlet being sufiiciently long to exceed in angular extent two yarn feed positions for the needles; a bafile dividing said inlet into separate openings; and another yarn severing device located at said battle for cutting yarn entering the inlet between said bafile and the other end of said inlet; each yarn severing device being an electrical resistance Wire effective to sever yarn when heated.

References Cited in the file of this patent UNITED STATES PATENTS 2,501,838 Bennett Mar. 28, 1950 2,602,313 :Reading July 8, 1952 2,746,275 Cobert May 22, 1956 2,824,436 Stack et a1. Feb. 25, 1958 2,908,154 Butler Oct. 13, 1959 2,952,148 Rather Sept. 13, 1960 3,019,628 Page Feb. 6, 1962 FOREIGN PATENTS 219,666 Australia Jan. 14, 1959 

